// Create a default configuration for the new GridField, allowing record editing
$config = GridFieldConfig_RelationEditor::create();
$config->addComponent(new GridFieldSortableRows('SortOrder'));
$config->addComponent(new GridFieldBulkEditingTools());
//$config->addComponent(new GridFieldBulkImageUpload());
// Create a gridfield to hold the student relationship
$columnField = new GridField(
'Banners', // Field name
'Banner', // Field title
Banner::get()->sort("SortOrder"), // List of all related students
$config
);
// Create a tab named "Students" and add our field to it
$fields->addFieldToTab('Root.Banners', $columnField);